1. Field of the Invention
This invention relates to a spacecraft, and more specifically to a spacecraft comprising a modular structure.
2. Description of the Related Art
Spacecraft are widely used for communicating between Earth stations, and are becoming more important for communications in regions of the world where other communication paths are not available. Ordinary geosynchronous (xe2x80x9cGEOxe2x80x9d) spacecraft at their present state of development require expenditure of propellant in order to aid in maintaining their attitude, and/or their location in space, that is, their station. When the propellant is exhausted, the utility of the spacecraft is ended, and a new spacecraft must be launched to take over the communication function. Thus, there is a substantial industry that engages in fabrication and launch of spacecraft, both for new communications functions, and for replacing spacecraft that become inoperable.
The fabrication and launch of spacecraft has in the past been very costly, at least in part because each spacecraft was custom-designed and built for a particular use. Thus, there is a need to produce spacecraft in a more cost-effective manner. One solution is to create a modular spacecraft structure. Aspects of each spacecraft that are unique to the particular mission that it is to serve have been resistant to modularization. Thus, custom designs are needed that require the attention of skilled engineers, and fabrication of the custom design is expensive, requiring extensive integration and testing (xe2x80x9cIandTxe2x80x9d), all of which increases the lead-time. Thus, it would be desirable to create a completely modular spacecraft structure. Prior attempts to modularize have been made, but have resulted in only limited modularity. There is still some amount of custom design that is necessary with known modular spacecraft.
The equipment carried by spacecraft generates heat as an inherent by-product of its operation. Heat rejection or dissipation is a constant concern and limiting factor of GEO spacecraft design. Because spacecraft operate in a vacuum or near-vacuum environment, heat rejection from the spacecraft is limited to radiant heat transfer. The amount of exposed surface area is one factor upon which radiant heat transfer depends. Thus, it would be desirable to maximize the surface area of the spacecraft by making a spacecraft as planar as possible. Prior spacecraft structures have provided for some planar aspects, but not a spacecraft structure that, in its entirety, is substantially planar.
It is an object of the present invention to provide an interchangeable module, which can be used to form a substantially planar spacecraft structure.
It is another object of the present invention to provide a spacecraft structure that facilitates servicing of the modules.
It is another object of the present invention to provide a spacecraft that minimizes wasted space.
It is another object of the present invention to provide a spacecraft that has increased heat rejection capability.
It is another object of the present invention to provide a spacecraft that has the ability to thermally and vibrationally isolate the individual modules.
To achieve the above and other objectives, the present invention provides a spacecraft comprising one or more interchangeable modules. The modules can be connected in a variety of ways, including in such a manner so as to thermally and vibrationally isolate the modules from each other. The modules allow for reduced IandT, reduced lead-time, facilitated servicing, and increased efficiency.
In a preferred embodiment of the present invention, the modules have first and second surfaces to facilitate heat dissipation and that cooperate to form a cavity in which spacecraft equipment can be mounted. The modules can be oriented in a stacked position to facilitate transport into orbit, or in a planar position to facilitate in-orbit operation. The planar configuration allows for increased heat rejection, which allows more equipment per unit volume to be used in a single spacecraft than current designs.